A comprehensive survey has been made of the main-line emission from hydroxyl molecules in OH/IR stars. A total of 41 new main-line emission sources are detected, 18 of which show masers in both main lines. The emission velocities generally show double-peaked 'shell structure' which tends to overlap that of the 1612 MHz velocities, suggesting that they may be at the same radius in the stellar atmosphere. A total of 55 stars was detected, most of which show classic double-peaked profiles centered on the stellar velocity. Nine of these stars have stronger emission at 1665 MHz than at 1667 MHz. The velocity correlation among the 1612, 1665, and 1667 MHz lines show a good qualitative support for the idea of competitive gain under saturated maser conditions.

Comments:
Spectral type was set to:
""S"", where only one peak was found.
""D"", where two peaks were found.

Probable cloud source OH56.4+0.7 removed

The columns for the blue- and red-shifted velocities were filled with the two highest peaks seen in the spectra. The velocity range over which emission was seen, was used to calculate the radial velocity vrad and the expansion velocity vexp of the shell.